Process of improving properties of rubber, and product



' Patented Jan. 5, 1932 "UNITED STATES PATENT OFFICE .roniv mceavacn, or LEONIA, new JERSEY,

' COMPANY,

ASSIGNOR T GENERAL RUBBER OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY PROCESS OF IMPROVING PROPERTIES OF RUBBER, AND PRODUGI.

No Drawing.

This invention relates to a process for improving the properties of rubber, and to the products, more improving the rated rubbers.

In rubber manufacturing operations it is physical properties of evapodesirable that during the manipulation and to separation between ties of rubbers,

treatment of the rubber certain properties be present, such as ease of breakdown, smooth milling, calendering and extruding, and in V general that the rubber be capable of conversion into a soft well plasticized material. In the case of the vulcanizate of such material, it is desirable in. many articles which are subjected to flexing, such as tires, hose, belting, etc., that therebe a maximum resistance the rubber and fibrous portions of thearticle caused by the flexing, and it is also desirable inmany rubber articles, such as tires, conveyor belts and foot wear, that there be a maximum resistance to abrasion. The present invention I relates primarily to improving the physical propercanized states, obtained by evaporating rub ber latex or other water dispersions of rubber.

fAn object of the invention is to provide a method for improving the physical properties of rubbers, both before and after their vulcanization, derived from water dispersions of rubber by drying. Another object is to. provide a method for improving the breakdown, calendering and extruding properties of such dried rubbers. Another object is to-provide a method for improving the flexing and abrasion resistance of vulcanized rubber articles formed from such dried rubbers. The invention also resides in the products of the process.

The invention consists broadly in incor- 4 porating in a water dispersion of rubber,

either simultaneously or consecutively, a volatile base salt of a higher fatty acid and a volatile base salt of a strong water soluble acid, and withdrawing moisture from the dispersion, and if desired vulcanizmg' the product.

The invention is particularly applicable to the improvement of all-solids-content-latex Application filer-- December 13, 1929.

particularly to a process for both in their raw and vulerties and Serial No. 413,938.

rubbers, that is, rubbers obtained by withdrawing moisture from natural rubber latex,

k but Iilt is also applicable to rubbers obtained alkali soaps are added to'an ammonia latex and the latter then dried, the abrasion resistance of the resulting rubber is improved to a considerable extent and the flexing resistance may also be increased somewhat, and a similar improvement is noted in the case'of formaldehyde preserved latex but not to so great an extent. However, the addition of the soaps in general produces a dried rubber which is hard and does not break down as easily on the mill and does not produce e evaporation of artificial latices. When as smooth calendaring and extruding a rubbar. When volatile base salts of strong acids are added to an ammonia or formaldehyde preserved latex and the latter then dried, the resulting rubber is greatly improved in its breakdown property and produces a soft,

- smooth milling and calendering rubber, and

the vulcanized rubber resulting from this is considerably improved in its flexing resistance, but its abrasion resistance is reduced or only slightly increased.

I have found that by the addition to latex of combinations of volatile base salts of higher fatty acids and volatile base salts of strong water soluble acids, the crude rubber obtained by evaporating the water contentof such latex as amines may be used, it is preferred for cheapness, to use the ammonium soaps of the acids. Mixtures of-the ammonium soaps of various of these acids may be employed, and there may also be used with good results, the

' ammonium salts or soaps of certain vegetable 7 and if desired, mixtures ofsalts of different for varying of time, and-thenieubject is also a monium phosphate.

acids may be used. In general, the acids should'be capable of decomposingammonium soa s and ammonium proteinates. The volatile 7 ase soap of the fatty acid and the volatile base salt of the strong water soluble acid may be added either simultaneously or consecutively.

As specific illustrations of the invention,

the following are given:

Example To latex preserved with ammonia and having a concentration of about 35%, there is added 1% of lauric acid in the form of ammonium laurate and of ammonium chloride, these latter figures being based on 100 parts of solids in the latex. The latex was then spray dried and the resulting rubberwas found to have a quick breakdown, and ahigh abrasion and flexing resistance when vul- I canized,

Example 2 To a similar latex there was added 1% of lauric acid as ammonium laurate and then 5% of phosphoric acid as secondary am- The latex was then spray dried and the resulting crude rubber was ioundto have aquick breakdown, good calendering and extruding properties and the vulcanized rubber had a good abrasion and flexing resistance.

Example '3 To a similar latex 1% of lauric acid as ammonium laurate was added and then 1% of monochloracetic acid as the ammonium salt. The latex was spray dried and the resulting crude rubber was found toohave excellent breakdown and milling properties and when vulcanized. to have a good a raslonand fle ing resistance. R

A standard method of determining the flexing resistance isto build up a pad of alternate plies off bric and the rubber stock to be tested, vulcanize this pad in a mold, cut

the vulcanized material into strips of standard size and then to flex the strips by bending them in a machine until the plies separate. V V

A standard method of determining abrasion resistance-is to form-small slabs of-the rubber stock to be tested, vulcanize the slabs device, The amount of Parts of material added r100 parts of spray driedru ber Physicd mannerisms Rela- 0 Relative tive Relative E flexing hardabrasion s fie H 0 O O 3?; 6 g e e Z Z 2 a a w B1 5 '6 n: m In D 3 g 83 2 5 2 1 225 184 100 L5 100 100 100 1.5 1 114 1 a y 100 100 1.5 1 122 1% 1.5 100 .100 l 5 1 105 100 Blank-wthout added substances gives the following valuee. 100 94 93.

Fatty acids palm oil. Fatty acids of cocoa-nut oil.

In all the above cases the ammonium compounds of the acids or oils were used.

It will be seen by a comparison of the tests (1) of the spray dried rubber blank, with similar stocks containing (2) only the ammonium soaps'of fatty acids, '(3) only the ammonium salts of strong water soluble acids, and (52 the combination of (2) and (3), that the exing resistance of (4) ofv merely being a mean between that obtained for each of the salts alone, is far greater than either of them. In the case where the ammonium soap of cocoanut oil was used, two flexing tests each gave 100, the

same as that given by thev .blank, and the average of two tests using ammonium lactate gave about 119, but the average of the test in which both the ammonium soa of cocoanut oil and the ammonium salt 0 lactic acid were used was 175. Similar results will in general be noted with the tests of other materials and with theitests for hardness and abrasion; The table shows that while by the addition of the combination the greatest relative improvement is in the flexing value, then marked decrease in the hardnes:

specification.

insteadthe fatty acid of of the rubber which is a measure of the improvement in millin properties, and the abrasion value is definitely increased over that of the blank. Therefor'e,'the result obtainedby the present invention is not the sum of the results obtained bythe use of the separate materials but goes far beyond such sum.

It has been found that where one part of cocoanut oil ,(as the ammonium soap) has been combined, with an ammonia latex, that to obtain the optimum effects from the standpoints of abrasion, flex-- ing and breakdown, about 4% should be used of ammonium phosphate or ammonium chloride, 1 76 of ammonium lactate and about 1% of ammonium chlor acetate.

. The invention is also applicable when a creamed latex is used, the only difference being' that, as the creamed latex contains a reduced amount of non-rubber solids, a smaller amount of the volatile base compounds is required, and in the case oflatex creamed a plurality of times a corresponding further reduction is made in the quantity of compounds added.

The figures above trative, and it is obvious that the optimum quantities of compounds to be added for vari- 0 ous conditions can be readily determined by experiment.

While the invention has been described as 1 applied to a natural rubber latex, it is applicable to any latex, natural or artificial, where similar conditions prevail.

Having thus described my invention, what I claim and desire to protect by Letters Patent is: f

1. A process for im rovin the roperties 40 of rubber in both its raw and v iilcanized state, which comprises incorporating in a rubber latex a volatile base soap of a higher fatty acid and a water soluble substance which hydrolizes to produce volatile positive ions and acid ions capable of decomposing ammonium soaps and proteinates, and drying to solid form.

2. A process for improving the properties of ruber in both its raw and vulcanized state, which comprises incorporating in a rubber latex a volatile base so'ap'ofa higher fatty acid anda water soluble substance which hydrolizes to produce'volatile positive ions and acid ions capable ofdecomposing ammonium soaps and proteinates,;aand drying the latex with retention of its water soluble constituents. v

3. A process for improving the properties 0 of rubber in both its raw and vulcanized state, which comprises incorporating in a rubber latex a Volatile base soap of a fatty acid having approximately'10-30 carbon atoms and a volatile base salt of a strong water soluble 5 acid capable o decomposing ammonium given are merely illussoaps and proteinates, and spray drying the mixture.

4. A process for improving the properties of rubber in both its raw and vulcanized state, which comprises incorporating in a rubber latex an ammonium salt of a higher fatty acid and an ammonium salt of a strong water soluble acid capable of decomposing ammonium soaps and proteinates, and drying with retention of water soluble constituents.

5. A process for improving the properties of rubber both in its raw and vulcanized state, which comprises incorporating in a rubber latex an ammonium soap of an acid selected from the group consisting of oleic, undecylenic, lauric, palmitic, margaric and stearic, and an ammonium salt of a strong Water soluble acid capable of decomposing ammonium soaps ing'to solid form.

6. A process for improving the properties of rubber in both its raw and vulcanized state, which comprises incorporating in a rubber latex a volatile base soap of a fatty acid having approximately 1030 carbon atoms and a volatile base salt of an acid selected from the group consisting of hydrochloric, hydrobromic, hydrofluoric, phosphoric, lactic, oxalic, citric, chloracetic, nitric, and sulphurousacids, and drying the latex to solid form. v

7. A process for improving the properties of rubber both in its raw and vulcanized state, which comprises incorporating in a rubber latex a volatile base soap of a fatty acid having approximately 10-30 carbon atoms, and a volatile base salt of a strong Water soluble acid capable of decomposing ammonium soaps and proteinates, drying the latex, and processing and vulcanizing the resulting rubber.

8. An a-ll-solids-content-latex rubber containing the hydrolization residuum of a volatile base salt of a higher fatty acid and a Volatile base salt of a water soluble strong acid capable of decomposing ammonium soaps and a proteinates.

9. An all-solids-content-latex rubber containing the hydrolization residuum of an ammonium salt of a fatty acid having approximately 10-30 carbon atoms and an ammonium salt of capable of decomposing ammonium soaps and proteinates.

10. The dried residue of a rubber latex, an ammonium salt of a fatty acid having approximately 10-30 carbon atoms, and an ammonium salt of an acid group consisting of hydrohalogen, phosphoric, nitric, sulphurous, lactic, oxalic, citric, and chloracetic acids. 7

l1. Vulcanized rubber comprising the dried and vulcanized residue of a rubber latex, a volatile base salt of a higher fatty acid, and a volatile base salt of an acid selected from a water soluble strong acid selected from the and proteinates, and dry-.

the group consistm g 'of hydrohalogen; phosphoric', nitric, sulp urous, lactic, oxalic, cit ric and chloracetic acids,

i ed at Passaic, county of Bergen, State v ofew Jersey, this 10th day of December,

JOHN McGAVACK. 

